Improved response rates and outcomes in children with B-ALL in the R/R setting were achieved by the approval of monoclonal antibody-based drugs such as blinatumomab, a bispecific T-cell engager targeting CD19 and T-cell receptor-CD3 complex in 2014 and inotuzumab ozogamicin, a cytotoxic anti-CD22-calicheamicin conjugate in 2017 as well as anti-CD22 or -CD19 CAR-T cell-based therapies, e.g., with tisagenlecleucel in 2017 [129]. Here, CD19 is linked to acute lymphoblastic leukemia.